The assembly of optical relay systems within flexible tubes is known in the art. For example, U.S. Pat. No. 7,530,945 to Rudischhauser, et al. describes a method for assembling an endoscope having an optical system with several components that are at least partially surrounded by a tube made of both a transparent and a shrunk material. The method includes introducing the optical components into the tube of transparent and shrinkable material to form a unit, followed by shrinking the shrinkable material of the tube for fixing the position of the components contained within the tube relative to one another. To ensure the proper positioning of the components relative to one another, the components are inspected through the transparent shrunk material of the shrunk tube. After proper positioning of the components is confirmed, the unit composed of the shrunk tube and the components contained therein is introduced into a tubular shaft of the endoscope.